KR100391981B1 - Apparatus for restoring data from signal transmitted by a plurality of antenna - Google Patents

Abstract

The present invention relates to an apparatus for reproducing data from a signal transmitted through a plurality of antennas, the apparatus comprising: a plurality of despreaders for reproducing a pilot signal and a data signal using the pilot Walsh code and the data Walsh code; A path controller for selectively activating a despreader, an antenna weighting signal generator for generating an antenna weighting signal using pilot signals output from the plurality of despreaders, and an adder for adding data signals outputted from the plurality of despreaders And a control unit for controlling the inverse converting unit, the path controller, and the adder according to a transmission method of a base station. According to the present invention, a receiver system for one mobile station terminal can be used for various base station transmit diversity methods such as OTD, TSTD, STD, TXAA, and the like.

Description

A device for reproducing data from a signal transmitted through a plurality of antennas {APPARATUS FOR RESTORING DATA FROM SIGNAL TRANSMITTED BY A PLURALITY OF ANTENNA}

The present invention relates to an apparatus for reproducing data from a signal transmitted through a plurality of antennas, and more particularly, to a receiver for a terminal that can be used for all of various techniques of base station transmit diversity.

The third generation cellular system, cdma2000, requires increased system capacity to provide not only voice but also high-speed packet data transmission. In order to achieve this goal, various limitations of wireless communication must be overcome. The biggest burden in mobile communication is fading by multipath. Fading causes severe degradation of the received signal.

The best way to overcome fading is to use a diversity technique, which includes transmit diversity and receive diversity. Diversity is a technique that provides multiple paths, either temporally, frequency, or spatially.

In contrast to the second generation CDMA cellular system, the cdma2000 system determines the system capacity because the forward link has a smaller channel capacity than the reverse link. This is because a maximum ratio combining may be applied to a received signal by applying reception diversity using two antennas at a base station. It is difficult to apply reception diversity using two antennas in a terminal because it burdens the terminal. In order to balance the channel capacity of the forward link and the reverse link, cdma2000 uses base station transmit diversity.

Transmission diversity techniques proposed to date include orthogonal transmit diversity (OTD), time switched transmit diversity (TSTD), selection diversity (STD), and transmit antenna array (TXAA). Of these methods, it is not clear that the superiority of providing the best trade-off in terms of performance versus implementation complexity is unclear. The best way depends on the given environment.

Accordingly, an object of the present invention is to provide a receiver for a terminal that can be used in all of the base station transmission diversity methods such as OTD, TSTD, STD, TXAA, and the like.

1 is a block diagram of a receiver for a terminal according to the present invention.

2 is a block diagram of an OTD transmitter and a receiver.

3 is a block diagram of a TSTD transmitter and a receiver.

4 is a block diagram of an STD transmitter and a receiver.

5 is a block diagram of a TXAA transmitter and a receiver.

[Description of Reference Symbol in Drawing]

101, 103: despreading unit

105: path controller

107: antenna weighting signal generator

109: adder

111: pilot signal synthesizer

113: data signal synthesizer

115: delay element

117, 119: route evaluator

In order to achieve the above object, the present invention provides a device for reproducing data from a signal transmitted through a plurality of antennas, the plurality of reproducing a pilot signal and a data signal using the pilot Walsh code and the data Walsh code. A despreader, a path controller for selectively activating the plurality of despreaders, an antenna weighting signal generator for generating an antenna weighting signal using a pilot signal output from the plurality of despreaders, and the plurality of despreaders And an adder for adding a data signal outputted from the controller, and a controller for controlling the inverse converting unit, the path controller, and the adder according to a transmission method of a base station.

Here, each despreading unit includes a pilot synthesizer for synthesizing a pilot signal by despreading the transmission signal by the pilot Walsh code, and a data synthesizer for synthesizing a data signal by despreading the transmission signal by the data Walsh code. And a delay element for delaying a transmission signal input to the pilot synthesizer and the data synthesizer for a predetermined time.

Here, the data synthesizer multiplies the despreading result of the transmission signal by the data Walsh code with the pilot signal and outputs the data signal.

Here, each of the despreaders further includes a path estimator for evaluating the phase and the gain of the pilot signal output from the pilot synthesizer, and the antenna weighting signal generator uses the output of the path estimator. To generate an antenna weighting signal.

Preferably, the despreading unit is composed of two.

Here, the two despreaders perform data reproduction using a data Walsh code that is twice as long as a single antenna and different from each other, and the path controller activates both despreaders. The control unit controls the despreader, the path controller, and the adder so that an adder alternately outputs data signals reproduced by the two despreaders.

Alternatively, the two despreaders perform data reproduction using a data Walsh code having the same length as that of using one antenna, and the path controller selectively activates the two despreaders according to a predetermined pattern. The control unit controls the despreader, the path controller, and the adder so that the adder outputs data signals reproduced by the despreader selected according to the pattern in a line.

Or the two despreaders perform data reproduction using a data Walsh code having the same length as that of using one antenna, and the path controller activates both of the despreaders. The control unit controls the despreader, the path controller, and the adder so that the adder adds and outputs the data signal reproduced by the spreader.

According to the present invention as described above, a receiver system for one mobile station terminal can be used for various base station transmit diversity methods such as OTD, TSTD, STD, TXAA, and the like.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a block diagram of a receiver for a terminal according to an embodiment of the present invention. As shown in FIG. 1, the receiver for a terminal according to the present embodiment includes two despreaders 101 and 103, a path controller 105, an antenna weighting signal generator 107, and an adder 109. have. Although not shown in FIG. 1, a controller for controlling the component according to a diversity scheme is further provided.

As shown in FIG. 1, the despreading units 101 and 103 transmit a pilot synthesizer 111 for synthesizing a pilot signal by despreading a signal transmitted from a base station by a corresponding pilot Walsh code and a data Walsh code. A data synthesizer 113 for synthesizing the data signal by despreading the signal, and a delay element 115 for delaying the transmission signal input to the pilot synthesizer and the data synthesizer for a predetermined time. The despreader 101 uses Walsh P1 as a pilot Walsh code used for pilot reproduction and Walsh T1 as a datawalsh code used for data reproduction, while the despreader 103 is used for pilot reproduction. Walsh P2 is used as a pilot Walsh code, and Walsh T2 is used as a data Walsh code used for data reproduction. A delay element 115 is used to compensate for a path difference existing between each antenna. In the present embodiment, only the despreading unit 103 is provided with the delay element 115.

Walsh T1 and Walsh T2 are determined by the diversity scheme. That is, when the receiver for the base station terminal according to the present embodiment is applied to the OTD, the Walsh T1 and the Walsh T2 are not the same, and the control unit (not shown) has a Walsh code twice as long as when the diversity is not applied. The despreading units 101 and 103 are controlled by However, when applied to TSTD, STD, and TXAA, Walsh T1 and Walsh T2 are the same and are controlled to have Walsh codes of the same length as when diversity is applied.

On the other hand, the data synthesizer 113 reflects the path characteristics to the data signal by multiplying the data signal reproduced by the despreading using the data Walsh code and the pilot signal reproduced through the pilot player.

As shown in FIG. 1, the receiver according to the present embodiment includes an antenna weighting signal generator 107, and the despreader 101 evaluates the path in relation to the antenna weighting signal generator 107. Pathestimators 117 and 119 are provided. The path estimator 117 evaluates the phase and the gain of the pilot signal output from the pilot synthesizer 111 in the despreader 101, and transmits a predetermined signal for the characteristic of the path to the antenna weighting signal generator 107. To pass. The path evaluator 119 in the despreader 103 is also the same. The antenna weighting signal generator 107 evaluates the characteristics of each path based on the outputs of the path evaluators 117 and 119 and generates control information for controlling the power of the signal transmitted from the corresponding antenna. This control information is fed back to the base station and controls the power of the signal transmitted by the two antennas installed in the base station. When the mobile station receiver according to the present embodiment is applied to STD, this control information consists of 1 bit, and when applied to TXAA, it consists of multi bits. The antenna weighting signal generator is a block that is only active for STD and TXAA. In the case of STD, a message is generated in one bit and transmitted to a base station through a feedback channel. In the case of TXAA, a message is generated in multi-bit and transmitted to a base station through a feedback channel.

The receiver according to the present embodiment also includes a path controller 105. The path controller 105 selectively activates the two despreaders 101 and 103 according to the diversity scheme. That is, when applied to OTD and TXAA, both despreaders 101 and 103 are activated. However, when applied to the TSTD, the base station activates the selected despreader according to the unique pattern using the antenna in the base station and according to the antenna selection message. The operation of this path controller 105 is controlled by a controller (not shown).

The receiver according to the present embodiment also includes an adder 109 for adding data signals output from the despreader. How the adder 109 adds the data signal is determined according to the diversity technique. First, when the receiver is applied to the OTD, the data signal output from the despreader 101 and the data signal output from the despreader 103 are alternately rearranged and output. When applied to TSTD and STD, the data signal of the selected despreader is simply output. When applied to TXAA, the data signals output from the two despreaders 101 and 103 are added together and output.

If the length of the Walsh code used when no diversity is applied is N, the proposed receiver basically operates in units of N chips. It is assumed that the 'pilot 1 synthesizer' and the 'data 1 synthesizer' receive signals from the transmit antenna 1, and the 'pilot 2 synthesizer' and 'data 2 synthesizer' receive the signals from the transmit antenna 2. It does not matter if it changes. The signal sent from each transmit antenna is regarded as a separate signal at the time of reception and demodulated. In other words, the timing is maintained by receiving independent pilots and independent time-tracking.

Table 1 summarizes the modes of a terminal receiver for base station transmit diversity according to the present invention. Receiver according to the present invention can be used for OTD, TSTD, STD, TXAA by adding a control circuit for controlling to perform the operation shown in Table 1. In Table 1, diffuser 1 refers to diffuser 101 and diffuser 2 to diffuser 103, respectively.

Hereinafter, each diversity will be described, and how the receiver according to the present invention performs the operation of the receiver corresponding to each diversity.

2 is a configuration diagram of an orthogonal transmit diversity (OTD) transmitter and a receiver, FIG. 2A is an OTD transmitter, and FIG. 2B is an OTD receiver.

In OTD, a channel coded and interleaved bit stream is divided into two different streams and simultaneously transmitted through different transmission antennas. Both antennas will always be used. Different Walsh spreading codes are assigned to give orthogonality between each bit stream. It can continue to be divided into three, four, and so on. When a common pilot is applied to one antenna, an auxiliary pilot is applied to another antenna. Let N be the length of the Walsh code used when diversity is not applied. At this time, Walsh T1 and T2 in FIG. 2A have a code length of 2N.

In FIG. 2B, the block 'D' represents a delay element for compensating for the path difference existing between each antenna. The separately demodulated symbol data is sorted through demux (or demultiplexer) blocks and passed to the next block, the combiner. Walsh T1 and T2 have a code length of 2N.

When the receiver according to the present embodiment is applied to the OTD, the two despreaders 101 and 103 are different from each other and use a data Walsh code having a length 2N that is twice as long as using one antenna. It is controlled to play. The path controller 105 is controlled to activate both despreaders 101 and 103, and the adder 109 controls the data signals reproduced by the two despreaders 101 and 103 to be alternately output. do. By this control by the control unit, the receiver according to the present invention shown in FIG. 1 performs the operation of the OTD receiver shown in FIG. 2B.

3 is a block diagram of a time stitched transmit diversity (TSTD) transmitter and a receiver, FIG. 3A is a TSTD transmitter, and FIG. 3B is a TSTD receiver.

In a TSTD, only one of the two antennas is used at any given time. The same Walsh code is used for each antenna. Like the OTD, if a common pilot is applied to one antenna, an auxiliary pilot is applied to the other antenna. When the length of the Walsh code used when no diversity is applied is N, the code length of Walsh T is N in FIG. 3A. The switch is operated such that each user moves between antennas by an irregular unique pattern. Irregular unique patterns should ensure that, on average, half the users must use one antenna.

In FIG. 3B, the same Walsh code is used for each antenna. Walsh T has a code length of N. The switch is operated such that each user moves between antennas by an irregular unique pattern. This pattern is known in advance to the mobile station through the exchange of information with the base station.

When the receiver according to the present embodiment is applied to the TSTD, the two despreaders 101 and 103 reproduce the data signal by using the data Walsh code having the same length (N) as the case where the antennas are the same and use one antenna. Controlled to. The path controller 119 is controlled to select two despreaders 101 and 103 according to the unique pattern used when the antenna is selected by the base station. The adder 109 is controlled to simply output the data signal of the despreader selected in accordance with the pattern. By this control by the control unit, the receiver according to the present invention shown in FIG. 1 performs the operation of the TSTD receiver shown in FIG. 3B.

4 is a configuration diagram of a selection diversity (STD) transmitter and a receiver, FIG. 4A is an STD transmitter, and FIG. 4B is an STD receiver.

STD aims to improve the performance of TSTD. Antennas used in TSTDs do not always guarantee the best signal to noise ratio (SNR) at the receiver of the terminal. Ideally, the base station selects the antenna that maximizes the terminal's received SNR to ensure the best performance. However, this is not possible because the base station does not know the state of the mobile communication channel. The presence of a feedback channel from the terminal to the base station indicates the antenna to guarantee a higher SNR at the terminal, thereby improving performance. In consideration of the channel capacity of the reverse link, the terminal gives antenna information to the base station through a one-bit antenna selection message. Antenna selection speed will have a big impact on STD performance.

In FIG. 4B, the Walsh T has a code length of N. The switch is determined from an antenna selection message generated at the antenna selector and forwarded to the base station. The antenna selection message is not used directly for switch selection, but after experiencing time delays such as round-trip delay and base station / terminal processing time.

When the receiver according to the present embodiment is applied to the STD, the two despreaders 101 and 103 reproduce the data signal by using the data Walsh code having the same length (N) as the case where the antennas are the same and use one antenna. Controlled to. The path controller 119 is controlled to select two despreaders 101 and 103 according to the antenna selection message. The adder 109 is controlled to simply output the data signal of the despreader selected in accordance with the antenna selection message. By this control by the control unit, the receiver according to the present invention shown in FIG. 1 performs the operation of the STD receiver shown in FIG. 4B.

5 is a configuration diagram of a transmit antenna array (TXAA) transmitter and a receiver, FIG. 5A is a TXAA transmitter, and FIG. 5B is a TXAA receiver.

TXAA transmits the same data through the two antennas using the same Walsh code. Before transmitting, weighting is given by using antenna information transmitted through a feedback channel from a terminal. Let N be the length of the Walsh code used when diversity is not applied. At this time, the code length of Walsh T is N in FIG. 5A. H1 (t) and H2 (t) are determined by antenna weights transmitted from the terminal through a feedback channel. By this value, the phase and gain of the signal transmitted through each antenna are adjusted so that the SNR is maximized when the terminal receives it.

In FIG. 5B, since the same data is transmitted through the two antennas using the same Walsh code, the result of the path 1 and the result of the path 2 are added to the combiner.

When the receiver according to the present embodiment is applied to TXAA, the two despreaders 101 and 103 reproduce the data signal by using the data Walsh code having the same length (N) as that of the same antenna and using one antenna. Controlled to. The path controller 105 is controlled to activate both despreaders 101 and 103. The adder 109 is controlled so that the data signals reproduced by the two despreading units 101 and 103 are added and output. By this control by the control unit, the receiver according to the present invention shown in FIG. 1 performs the operation of the TXAA receiver shown in FIG. 5B.

This embodiment is only for illustrating the present invention, and is not intended to limit the scope of the present invention. Therefore, those skilled in the art should note that various modifications or changes can be made from the present embodiment.

According to the present invention as described above, a receiver system for one mobile station terminal can be used for various base station transmit diversity methods such as OTD, TSTD, STD, TXAA, and the like.

Claims (8)

An apparatus for reproducing data in a signal transmitted through a plurality of antennas, A plurality of despreading units for reproducing the pilot signal and the data signal using the pilot Walsh code and the data Walsh code; A path controller for selectively activating the plurality of despreaders; An antenna weighting signal generator configured to generate an antenna weighting signal using a pilot signal output from the plurality of despreaders; An adder for adding data signals output from the plurality of despreaders; A control unit for controlling the inverse converting unit, the path controller, and the adder according to a transmission method of a base station; A data reproducing apparatus, comprising: The method of claim 1, Each despreading unit A pilot synthesizer for synthesizing a pilot signal by despreading the transmission signal by the pilot Walsh code; A data synthesizer for synthesizing a data signal by despreading the transmission signal by the data Walsh code; Delay element for delaying the transmission signal input to the pilot synthesizer and the data synthesizer for a predetermined time And a data reproducing apparatus. The method of claim 2, And the data synthesizer multiplies the despreading result of the transmission signal by the data Walsh code with the pilot signal to output the data signal as a data signal. The method of claim 2, Each of the despreaders further includes a path estimator for evaluating the phase and the gain of the pilot signal output from the pilot synthesizer, wherein the antenna weighting signal generator uses the output of the path estimator to output an antenna. And a data reproducing apparatus. The method of claim 1, And said despreading unit is comprised of two pieces. The method of claim 5, The two despreaders perform data reproduction using a data Walsh code that is twice as long as a single antenna and different from each other, and the path controller activates both of the despreaders. And the controller controls the despreader, the path controller, and the adder to alternately output data signals reproduced by the two despreaders. The method of claim 5, The two despreaders perform data reproduction using a data Walsh code having the same length as that of one antenna, and the path controller selectively activates the two despreaders according to a predetermined pattern. And the control unit controls the despreader, the path controller, and the adder to output the data signals reproduced by the despreader selected according to the pattern in a line. The method of claim 5, The two despreaders perform data reproduction using a data Walsh code having the same length as that of using one antenna, and the path controller activates both of the despreaders, and the plurality of despreaders And the control unit controls the despreader, the path controller, and the adder to output the data signal reproduced by the adder.